Modélisation des transformations pour l'évolution de modèles multidimensionnels

La modélisation et l'entreposage des données ont constitué, depuis plus d'une décennie, une problématique de recherche pour laquelle différentes approches ont été proposées. Ces approches se focalisent sur des aspects statiques de l'entrepôt de données. Or, l'évolution du système d'information qui alimente un entrepôt peut avoir un impact sur ce dernier et peut conduire, par conséquent, à l'évolution de son modèle multidimensionnel. Dans ce contexte évolutif, nous proposons une démarche dirigée par les modèles pour automatiser la propagation de l'évolution du modèle de la source de données relationnelle vers l'entrepôt. Cette démarche est fondée sur deux modèles d'évolution ainsi qu'un ensemble de règles de transformation formalisées en Query/View/Transformation. Nous développons un prototype logiciel nommé DWE (« Data Warehouse Evolution ») qui supporte cette démarche

A Prototyped NL-Based Approach for the Design of Multidimensional Data Warehouse

Organizations are more and more interested in the Data Warehouse (DW) technology and data analytics to base their decision-making processes on scientific arguments instead of intuition. Despite the efforts invested, the DW design issue remains a great challenging research domain. The design quality of the DW depends on several aspects, as the requirement gathering. In this context, we propose a Natural Language (NL) based design approach, which is twofold, first, it facilitates the involvement of the decision-makers in the DW design process; indeed, NL can encourage the decision-makers to express their requirements as English-like sentences conform to NL-templates. Secondly, our approach aims to generate semi-automatically a DW schema from a set of requirements gathered as analytical queries compliant to the NL-templates. This design approach relies on (i) two easy-to-use NL-templates to specifying the analysis components, and (ii) a set of five heuristic rules for extracting the multidimensional concepts from the requirements. We demonstrate the feasibility of our approach by developing the prototype Natural Language Decisional Requirements to DW Schema (NLDR2DWS)

Galaxy-Gen: A Tool for Building Galaxy model from XML documents

National audienceA galaxy model is a multidimensional model dedicated for XML document warehouses. It can be seen as a network of entities (i.e., dimensions) connected via nodes. After giving an overview of our four-steps semi-automated method for the generation of galaxy models which aims to build data marts from XML documents. This paper focuses on the software tool, called Galaxy-Gen that implements the proposed method. We illustrate the Galaxy-Gen functionalities and make its first assessment through two experiments. The first experiment is applied to a set of twenty XML documents taken from the academic domain. The second one addressed a set of 1691 XML documents issued from the Clef-2007 collection. The assessment is performed by comparing manual design galaxy models with those produced by the Galaxy-Gen tool. The results are very promising

Structuration sémantique des documents XML : Expérimentations et évaluation

National audienceLa norme XML permet la représentation d'un document selon un découpage logique qui ne reflète généralement pas la sémantique de son contenu. Il serait donc intéressant de compléter la structure logique des documents XML par une structure sémantique. L'objet de cet article est alors d'évaluer l'approche d'extraction de structures sémantiques pour les documents XML que nous effectuons sur un échantillon de documents issus de la collection ImageClef 2010 tout en utilisant le thésaurus MeSH (Medical Subject Headings)

OLAP4Tweets: Multidimensional Modeling of tweets

International audienceTwitter, a popular microblogging platform, is at the epicenter of the social media explosion, with millions of users being able to create and publish short posts, referred to as tweets, in real time. The application of the OLAP (On-Line Analytical Processing) on large volumes of tweets is a challenge that would allow the extraction of information (especially knowledge) such as user behavior, new emerging issues, trends… In this paper, we pursue a goal of providing a generic multidimensional model dedicated to the OLAP of tweets. The proposed model reflects on some specifics such as recursive references between tweets and calculated attributes

Modèle multidimensionnel en diamant dédié à l'OLAP sémantique de documents

National audienceLe document électronique représente aujourd’hui un support d’information que les entreprises ne peuvent plus négliger si elles veulent être certaines d’identifier et de gérer toutes les données qui leur sont utiles au quotidien. Plusieurs travaux ont proposé l’application des techniques OLAP (« On-line Analytical Processing ») aux informations documentaires. Dans cet article, nous présentons un nouveau modèle multidimensionnel dédié à l’OLAP de documents. Ce modèle, dit en diamant, est organisé autour d’une dimension centrale qui traduit la sémantique du contenu textuel du document

A novel multidimensional model for the OLAP on documents : modeling, generation and implementation

International audienceAs the amount of textual information grows explosively in various kinds of business systems, it becomes more and more essential to analyze both structured data and unstructured textual data simultaneously. However information contained in non structured data (documents and so on) is only partially used in business intelligence (BI). Indeed On-Line Analytical Processing (OLAP) cubes which are the main support of BI analysis in decision support systems have focused on structured data. This is the reason why OLAP is being extended to unstructured textual data. In this paper we introduce the innovative “Diamond” multidimensional model that will serve as a basis for semantic OLAP on XML documents and then we describe the meta modeling, generation and implementation of a the Diamond multidimensional model

Diamond multidimensional model and aggregation operators for document OLAP

International audienceOn-Line Analytical Processing (OLAP) has generated methodologies for the analysis of structured data. However, they are not appropriate to handle document content analysis. Because of the fast growing of this type of data, there is a need for new approaches abling to manage textual content of data. Generally, these data exist in XML format. In this context, we propose an approach of construction of our Diamond multidimensional model, which includes semantic dimension to better consider the semantics of textual data In addition, we propose new aggregation operators for textual data in OLAP environment

OLAPing Reflexive Multidimensional Fact

The multidimensional data model and implementations of social networks come with a set of specific constraints, such as missing data, reflexive relationship on fact instance. However, the conventional OLAP operators and existing models do not provide solutions for handling those specificities. Therefore, further efforts should be invested to extend these operators to take into consideration the specificities of multidimensional modeling of tweets and their manipulation. Face to this issue, we propose, in this paper, two new OLAP operators that enhance existing solutions for OLAP analyses involving a reflexive relationship on the fact instances. For each OLAP operator, we suggest a user-oriented definition as an algebraic formalization, along with an implementation algorithmic

Assessment of the Addition of Fluorapatite in Hydroxyapatite Coatings: Implementation Prosthetics/Bone in Vivo

Hydroxyapatite (Hap: Ca10 (PO4)6 OH2)-Fluorapatite (Fap: Ca10 (PO4)6F2) composite coating on 316 L stainless steel, using the High-Velocity Oxy-Fuel Spray (SHVOF), was investigated. This work is an evaluation of the bioactivity of bone/Hap–Fap composite coatings implanted in the tibia of the rabbit. A small amount of Fap (6.68, 13.26 and 26.52 w% Fap attributed to 0.25, 0.5 and 1% fluor) was introduced into Hap. The fluorapatite provides more stable and adherent deposits. The characteristics of the coatings were investigated with various instruments including Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) and biological (in-vivo and in-vitro) tests. Hap−Fap coating showed excellent behavior in vitro and in vivo tests revealing that the Fap is effective in improving biocompatibility and bioactivity. This study draws inspiration from technological and biological selection solutions adopted by evolution, to transpose the principles and processes of human engineering